Geological History of the Pyrenees

Mesozoic and Cenozoic Geological History of the Pyrenees

Mesozoic and Cenozoic Geological History of the Pyrenees

Introduction

This article discusses the geology of the mountain range of the Pyrenees. These take birth there are about 40 million years, instead of a shallow sea, by the collision of the Iberian plate with the Eurasian plate, sedimentary strata base Hercynian (-400 to -245000000 years) are then reassembled. Accordingly, although the chain is young in the geological sense, it is composed mainly of formerly formed rocks (rocks metamorphic, volcanic and plutonic Hercynian basement as granitoids , or sedimentary rocks of Permian ), post-Hercynian younger rocks are minority (sedimentary rocks) and being in low mountains or the plains (Vergés et.al, 2002).

Intracontinental Pyrenees branch is located to the north-west of system Alpine orogeny totaling an impressive length of 12 000 km. In the narrow sense, the Pyrenees extend the Bay of Biscay in the west to the Gulf of Lion and the Gulf of Rosas in the east, about 430 km, width varying simultaneously between 65 and 150 kilometres. Their northern limit is underlined by the North Pyrenean forehead (frontal thrust or North Pyrenean abbreviated CFNP), an overlap causing major strata of the North Pyrenean area on their foreland to the north - the Aquitaine basin . Their southern boundary is drawn by the South Pyrenean forehead (frontal thrust or South Pyrenean abbreviated PSTC), also a major overlap placing marginal Sierras and their equivalents on their southern foreland - the Ebro basin.

Off (and geologically correct) direction, the Pyrenees continue west in the Basque Mountains and then in the Cantabrian Mountains (called Basque-Cantabrian chain). Finally they disappear off the Asturias. In a similar manner to the east they do not stop suddenly to the Gulf of Lion, but still an arcuate manner in layers of Corbieres, across the bottom Languedoc and end in Provence Southern. Here folds with structuring typically Pyrenean gradually transposed by folds with typical alpine structure. Further east there remains only the Alps. The Pyrenees wider therefore reach a length of about one thousand kilometers.

Before the Late Cretaceous sedimentation area of the Pyrenean area is divided into two facies. North 'of Iberia (South Pyrenean axial zone and zone) are deposited carbonate platform with very limited due to several emersions thicknesses. In the North Pyrenean zone establishes a deep furrow strongly subsiding, which was caused by shear in crust distension (transtensifs movements -. Engl transtension ). This path follows the west / east old Variscan fractures and is divided into two branches by massive satellites of the North Pyrenean zone (the aturien furrow south with 2,500 meters of flysch slate and northern trench with black flysch ) . It sinks towards the Atlantic and cushions before Aude. To the north it is accompanied by relatively stable Aquitaine platform. It is very likely that there was a significant crustal extension extending the rift in the Bay of Biscay.

This transtensive distension is probably the cause of the Pyrenean metamorphism, which is characterized by a heat ...